The present invention relates to a method for manufacturing a printed wiring board, in which an electric device is embedded in an insulating base member, and to the printed wiring board manufactured by the method.
Conventionally, a printed wiring board, in which an electric device is embedded in an insulating base member for achieving high density packaging of the electric devices, is known.
For example, there is an art disclosed in JP-A-11-312868. In the art, a plurality of first resin films that make up an insulating base member are formed. The first resin films include thermosetting resin in B stage. A plurality of vias are formed in each first resin film. A plurality of conductive layers are formed on a surface of each first resin film. Then, a second resin film is formed. The second resin film has a glass transition temperature higher than the curing temperature of the first resin films. An electric device sealed with resin is mounted on the second resin film. The second resin film is stacked with and pressed with the first resin films to form an integrated body of the first and second resin films. Subsequently, the thermosetting resin included in the first films is cured by heating the integrated body to manufacture a printed wiring board, in which the conductive layers are electrically interconnected by the vias, the electric device is electrically connected to the conductive layers, and the electric device is embedded in the insulating base member.
However, in the art of the publication, there is a difficulty in the alignment of the electric device with the insulating base member, which is formed when the thermosetting resin included in the first films is cured, in the printed wiring board because the second resin film, on which the electric device is mounted, is clamped between and stacked with the first resin films. Therefore, a relatively great deviation in the alignment can cause a defect in electrical contact between the electric device and the vias.
There is another art disclosed in JP-A-4-356998. In the art, a recess is formed by counter boring in an insulating base member of a double-sided board, which makes up an inner layer board of a multilayered board. Then, an electric device is placed in the recess and soldered. Afterward, the double-sided board, on which electric device is soldered, is multilayered by stacking and pressing pre-pregs on both surface of the double-sided board to manufacture a printed wiring board with the embedded electric device.
However, in the art of JP-A-4-356998, the manufacturing process is complicated and the number of manufacturing steps increases because the pre-pregs are separately piled on the double-sided board.